Operation of printing apparatus by radio



D. B. PERRY OPERATION oF PRINTING APPARATUS RY RADIO Filed March 29. 1924 EL, EN INVENTOR far 155'/ A TTO RNE Y May 5, 1925.

www P receiving DONALD IB.

. i I I V L i J PERRY, OF YONKERS.- NEW YORI, ASSIGNOR TOy AMERICAN TELEPHONE AND TELEGRAPH COMPANY; A CORPOATION OF NEW YORK.

' y OPERATION OF PRINTING APPARATS BY RADIO.

Application filed.` March l29,1924. 4Serial No. 702,877.`

.5 vented certain Improvements in Uperatio of Printing Apparatus by Radio, of which Athe following is a specification.

This invention relates to radio signaling and more particularly to the transmission of printing telegraph messages by means of radio. l

Printer intercommunication by radio on the half-duplex basis presents certain diiculties, particularly in the matter of breaking by a receiving operator to obtain control ofthe circuit for sending. In ordinary radio telegraph service, except Where special provision is made for duplex oper-` ation, it is necessary for a station that is receiving to wait until the sending operator stops and listens before it may send. This method, if applied to printer service, will result in unsatisfactory service and no break feature. l A

It is one of the` purposes of the present invention to connect a combination radio transmitter and receiver to a printer circuit in such a manner as to permit of an instantaneous break, This result may be accomplished by arranging two intercommunicating stations so that normally each station will send out a different wave length. At the sending station the wave length transmitted' will have impressed thereon code combinations set up by the transmitting apparatus of a printing tele` graph set. `At both the transmitting and receiving stations a beat frequency may be obtained corresponding to the difference between the two radiated wave lengths, and upon this beat frequency the` code combinations will be superposed. At each station the beat frequency will be selected and the code combinations will be detected therefrom to operate the receiving printer.

In asystem such as above outlined, the

station will be radiating a continuous wave. By merely interrupting the continuous wave emitted from the receiving station the receiving operator may break the circuit, for the beat frequency will no longer be present and consequently the code combination Sent out from the transmitting station will not be impressed upon the final detector at either the' transmitting or receiving` station. The sending operator will no longer receive his own copy and the printer circuit may beJ arranged in a Well known manner so that under these conditions a break relay will be :operated to stop the transmitter and give an audible or visual signal.

Further details and object of the invention will be clear from the following description when read in connection with the accompanying drawing, the figure of which illustrates a preferred embodiment of the invention. Y

Referring to the drawing., TB; designates a radio antenna with which is associated a circuit of the vacuumtubeO, arranged to generate and transmit from the antenna oscillations of a wave length differing from those radiated from a distant station by a definite beat frequency. The circuit of the vacuum tube O is controlled by the sending relay 10, which transmitting printer TP, the circuit being normally closed when the transmitter TP is not actuated. Code combinations set up,

by theV transmitter TP `cause the sending relay 10 to successively. interrupt the plate circuit -of the vacuum tube O to impress the code combinations upon the W'ave length transmitted.

The vacuum tube oscillator O also functions as a detector to detect the beat note due to interaction of the wave length radiated lfrom a distant station and the wave length radiated 'from the station under consideration. vThen code combinations are impressed upon either one of the wave lengths the beat frequency vacuum tube O will be interrupted in accordance with the .cod combination. A band filter BF, of awell known type, is associated with the plate circuit of the vacuum tube O to select the beat note carrying the code lcombination and impress it upon a suitable vacuum tube amplifier A. A vacuum tube detector D, of a well known type, is associated with the output circuit of the amplifier and functions to detect from the. beat note the code combination which is impressed upon one or the other of the radio frequencies, depending upon whether the station illustrated is transmitting or whether the distant station is transmitting.

A receiving relay R is provided, said receiving relay having three windings. One

is associated with the.'

detected by the ofthe windings 1l CTI ' i11g13 isa through the voperating winding 11; when the beat note is being received. is so adjusted by means.

the winding 11 and the winding 12 will betoinc effective to shift the armature 15 so that the circuit of the line relay LR is held open. 'hen the beat note is impressed upon thc detector D, however,

are actuated. receiving printer apparatus RP also comprises a distributor RD of the start-stop type, which The circuits of suitable selecting magnets 1 to 5 inclusive are controlled as the distributor rotates by means of the line relay LR. he transmitting and receiving printing apparatus are special break distributor Under normal the circuit of the break passes over the beat note 1s not present,

station, the will be closed by the line relay LR as the brush of the transmitting passes over, the break segment B. The break relay operates to light a lamp' S and to hold open the circuit of the start magnet 16 to prevent further operation of the transmittin distributor.

Further etails of the invention will now be clear fromA the description ot' the opera is as follows: When the transprinter TP 1s not actuated, the cirg relay 10 is closed over inner ring of the dispressed upon the vacuum tube O. Wave lengths beat with veach other duce a beat frequency in the plate circuit which will be selected by the band filter BF, amplified by the amplifier A and im` pressed upon the detector D to cause a steady plate current to flow in the output circuit of the detector D and through the operating winding 11 of the receiving relay is causes the armature 15 of the receiving relay to hold the circuit of the line relay LR closed.

to. pro* will be actuated so that certain of the contacts 1 to 5 inclusive willv make contact with the bus-bar, depending upon the code combination to be transmitted. At the same time, tie start Contact 18 will be closed to comthe Winding of magnet 16, over the start segment S of the distributor Tl), over the brush ol thefdistributor and thence to battery over the segment 19. 'Ihe stai-t magnet trips the brush z which conimcnces to rotate in a clockwise direction.

impulse is transmitted. the plate circuit of the that the b This impulse opens vacuum tube O so Returning to the sta-Ation illustrated, the interruption of thev beat note causes the plate current normally flowing inthcoutput circuit of the detector D to be interrupted with the result that the biasing Winding 12 shifts the armature -15 of the receiving relay R- and opens the circuit of the line rlelay LR.. AA circuit is therefore completed from battery, over the back righthandl contact of rela-y LR, over a segment of the innenring of the receiving distributor RD, over the brush arm of the distributor, and a `segment of the outer ring ot' the distributor RD and through the winding of the start magnet 17 to ground. The start magnet accordingly trips the brush arm of the receiving distributor RIT so that the brush arm begins to rotate in a clockwise direction. A similar action of the receiving apparatus takes place at the distant station. As the brush arm of the transmitting distributor TD continues to rotate, it passes over the segments 1 to 5 inclusive ot' the outer ring of theV distributor and thereby transmits either open or closed circuit impulses ,to the sending relay 10, depending upon vthe selective position oi thecontacts of the transmitter T. As the brush arm passes over a grounded transmitting segment theirelay 10 will close the plate circuit of the oscillator O so that the normal Wave length of the station will be radiated and a beat note Will appear in the plate 1 circuit due to-the interaction of the radiated Wave, length andthe received Wave length. A similarbeat frequency `Will, of course, 'be produced in the plate circuit of the oscillator tube at the distant receiving station. At both stations the beat frequency will be passed through the filter BF, amplified by the amplifier A and impressed upon the detector D to produce a direct current component through the operating Winding 11 of the receiving relay R. This causes contact 15 .to close the circuit of' the line relay LR.

As the brush arm of the transmitting distributor TD passes over an ungrounded transmitting segment, the circuit of the sending relay 10 Will be open and the ensuing circuit operation will be the same as that described in connection With the transmisvsion of the starting impulse. In short, each time the sending relay 10 transmits a 'closed circuit impulse the receiving relay LR at the local station and the corresponding relay at the distant station receive a closedI circuit impulse. Likewise, each time the sending relay 10 transmits an open circuit impulse the circuit of the line relay LR at the local station and the circuit of the similar relay at the distant station Will be open. Y

As the brush arm of the receiving distributor RD rotates it passes over the sucther cessive segments 1 to 5 inclusive of-its outer ring coincident with the receiving of an open or ciosed circuit impulse through the line relay LR. It' a closed circuit impulse is received a circuit will be completed over Vthe left-hand front contact of the line relay and over the corresponding segment in the outer ring of the receiving distributor Rl) to one of the selecting magnets 1 to incl-usive. If an open circuit impulse is received by the line relay the circuit of the corresponding selecting magnet will not be conipleted. A similar operation takes place at the receiving printer of the distant station.

, As the brush arm of the transmitting distributor TD passes onto the sixth segment of the outerring a closed circuit condition' is established for the sending relay 10 and the final step impulse is transmitted. The

line relay LR accordingly receives a closed` circuit impulse; as does the. similar line relay at the distant station.' Consequently, as the brush arm of the receiving distributor RD returns to its initial osition the circuit of the start magnet 17 will be held open at the right-hand contact of the line relay LR until the start impulse of the succeeding code combination is transmitted. rl`he brush arm accordingly is brought to rest by coaction with the latch of the start magnet. Just before the brush arm asses to its initial position it closes a circuit lfrom the grounded segment of the inner ring of the receiving distributor and over the corresponding segment in the outer ring, through the print magnet 19, which causes acharacter to be printed, determined by the combination of selecting magnets actuated during the selecting operation, as is Well understood in 'the art. The operation of the re'- ceiving printer atthe 'distant receiving station Will be similar to that just described.

Let us now assume that the operator at the distant receiving station desires to break.

in. The distant operator will then open/the key corresponding to BK at that station, thereby holding open the circuit of the sending relay corresponding to l0 at that station. This Will continuously interruptthe plate circuit of the oscillator corresponding to O at the distant receiving station, with the result that the Wave length normally radiated from the distant station will no longer be received in the circuit of the oscil- .lator O at the station illustrated. T he beat note Will therefore no longer be transmitted through the band ilter BF and no closed circuit impulses will pass through the operating Winding 11 of the receiving relay R. Consequently, the armature 15 of the receiving relay R will hold open the circuit of the line relay LR as long as the break key BK is held open at As the brush arm ofv the transmitting distributor TD passes over the sixth segment the distant receiving station. n v

tact ot the line relay LR, through the lower Winding of the break relay BR, over the break segment B, brush and segment 19 of the distributor TD to battery. A momentary circuit is thus closed through the lower winding of therbreak relay as the brush arm passes over the break se ent Bao that the break relay BR is energized. A"-epircuit is completed by the break relay through its locking winding over itsupper front contact in series With the break signal S. At its lower armature the break relay BR holds open the circuit of the start magnet .16 and when the brush arm 19 comes to rest the brush arm can nolonger be released in response to the closing of the start contact 18 as the sender T is further operated.

pon observing the signal lamp S the operator at the station illustrated (which, as described, was sending) will open the release key RK, thereby unlocking the break f relay BR. The operator also ceases to transmit by means of the transmitter T as soon as the break signal is observed, and as the circuit is now in its normal position the operator at the distant station may begin to transmit signals in the o posite direction. The transmlssion of signa s fromthe distant station after the breaking operation will be obvious without further description as the circuit at the distant station is identical in all respects with that illustrated.

VTo aid in properly tuning the variable condenser in the circuit of the antenna TR, an ammeter 2O is shown connected in circuit with the operating winding of the receiving relay R. A change in the by the desired statlon, thereby producing beat note, which will' be passed through the stand-by th frequency near that emitted te litude of the wave rauced while tuning in in alter BF. The Aam diated should be For this purpose, the' grid connection of the oscillator may be varied, y means of the adjustable .resistance 21 to increase the negative with the distant station. e operator, while tuning, will thrw the switch 22 to substitute a telephone receiver 23 for the receiving relay R. This is done for the reason that the operator will determine whether or not the desired station is signaling by receiving the signals transmitted from the distant intercommunicating stations and these signals will be so weak, because of the reduced amplitude of the frequency emitted by the station which is tuning in, that the will not operate the receivingrelay. They my be readily heard in the receiver 23, however, so that the perator will know that the desired station is busy.

It will be obvious that the general t princlples l1ere1n disclosed may be embodied in without departing from the spirit of the invention as defined llowing claims.

What isl claimed "is:

1. a radio signaling system, a plurality of intercommunicating stations, each station frequency, means at each station for producing a beat superposed frequency produced at' each may be interrupted when the receiving operator desires to break in, thereby causing' eat frequency to cease, and means at the station which is sending responsive to the interruption ofv the beat frequency to operate a break signal atsaid station.

In a radio signaling system, a plurality of intercommunicating stations, each emitting a wave having a dilerent frequency, means at each station to produce a beat frequency between the Wave rco f tion,

and means at the station which is sending responsive to the interruption of the beat fre uency to actuate a signal to indicate the brea 3. In a radio signaling system, a plurality of intercommunicating stations, each emitting a Wave having a different frequency,

`means at each station to produce a beat frequency by the interaction of the Wave emitted with the Wave received, an automatic signal transmitter at each station, means controlled by said automatic signal transmitter to impress corresponding signal variations upon the Wave emitted from that station, thereby producing similar signal variations upon the beat frequency at each station, means to detect the transmitted signals produced by the automatic signal transmitter from the beat frequency at each station, means at the station which is receiving for interrupting the Wave emitted therefrom When it is desired to break, thereby interrupting the beat frequency at both stations, and means responsive to the interruption ofthe beat frequency at the sending station to stop said automatic signal transmitter.

4:. In a radio signaling system, a plurality of intercommunicating stations, each emitting a Wave having a different frequency, means at each station to produce a beat frequency Wave emitted With the Wave received, an automatic signal transmitter at each station, means controlled by'said automatic signal transmitter to impress corresponding signal variations upon the Wave emitted from that station, thereby producing similar signal variations upon the beat frequency at each station, means to detect the transmitted signals produced by the automatic signal transmitter from the beat frequency at each station, means at the station which is receiving for interrupting the Wave emitted therefrom When it is desired to break, thereby interrupting the beat frequency at both stations,

' and means responsive to the interruption of the beat frequency at the sending station to stop said automatic signal transmitter and actuate a signal to indicate the break.

5. In a radio signaling system, a plurality of intercommunicating stations, each emitting a Wave having a different frequency, means to produce a beat frequency at each station by the interaction of the Wave emitted with the Wave received thereat, a printing telegraph transmitter at each station, means controlled by said transmitter at a station which is signaling for impressing code impulses upon the Wave emitted from that station, thereby causing similar code impulses to be superposed upon the beat frequencies produced at both stations, means to detect said code impulses from the beat frequenc at each station, a receiving printer at eac A by the interaction of theA station responsive to the detected code iin-l `pulses to print a character corresponding to each code combination, tion which is receiving for interrupting the wave emitted from that station when it is desired to transmit a break signal, thereby interrupting the beat frequency at both stations, and means responsive to the interruption of the beat frequencyl at the station which is sending to stop said printingtelegraph transmitter.

6.. In a radio signaling system, a plurality. of intercommunicating stations, each emitting a Wave having a different frequency, means to produce a beat frequency at each station by the interaction of the Wave emitted With the Wave received thereat, a printing telegraph transmitter at each station, means controlled by said transmitter at a station which is signaling for impressing code impulses upon the Wave emitted from that station, thereby causing similark code impulses to be superposed upon the beat frequency produced at each station, means to detect said code impulses from the beat frequency at each station, a receiving printer at each station responsive to the detected code impulses to print a character corresponding to each ycode combination, means at the station which is receiving for interrupting the Wave emitted from that station when it is desired to transmit a break signal, thereby interrupting the beat frequency at both stations, and means responsive to the interruption of the beat frequency at the station which is sendin to stop said printing telegraph transmitter and actuate a signal to indicate the break. 7. In a radio signaling system, a plurality of intercommunicating stations, each emitting a wave having a different frequency, means at each station to produce a beat fre quency by the interaction of the Wave emitted from that station with the Wave being received thereat, a printing telegraph transmitter at each station for setting up code combinations, a distributor associated with each transmitter for successivel impressing the impulses of the code combination upon the Wave emitted from the corresponding station, thereby causing similar code combinations to be impressed upon the beat frequency produced at both stations, means at each station for detecting from the beat frequency the code combinations impressed thereon, a receiving printer at each station, a distributor associated withveach receiving printer for impressing upon the elements of the printer the impulses of the detected code combination, means at -the station Which is receiving signals for interrupting the wave emitted therefrom when it is desired to transmit a break signal, thereby interrupting the beat frequency atv both sta tions, and means responsive to the interrup means at the stated therefrom tion of the beat frequency at the station which is sending to stop the distributor associated With the transmitter thereat.

8. In a radio signaling system, a plurality of interconmnmicating stations, each emitting a Wave having a different frequency, means at each station to produce a beat frequency by the interaction of the Wave emitted from that station with the Wave being received thereat, a printing telegraph transmitter at each station for setting up code combinations, a distributor associated with each transmitter for successively impressing the impulses of the code combination upon the Wave emitted from the corresponding station, thereby causing similar code combinations to be impressed upon the beat frequency produced at each station, means at each station for detecting from the beat frequency the code combination upon the Wave emitted from the corresponding station, thereby causing similar code combinations to be impressed upon the beat frequency produced at both stations, means at each station for detecting from the beat frequency the code combinations impressed thereon, a receiving printer at each station, a distributor associated with each receiving printer for impressing upon the elements of the printer the impulses of the detected code combination, means at the station which is receiving signals for interrupting t-he Wave emitwhen it is desired to transmit a break signal, thereby interrupting the beat frequency at each station, and' means responsive to the interruption frequency at the station which is sending to stop the distributor associated Wi-th the transmitter thereat and to actuate a special signal to indicate the break.

9. In a radio signaling system, a plurality of intercommunicating stations, each station emitting a Wave having a different frequency, means to produce a beat frequency of the beat at each station by the interaction of the Wave emitted with the wave received thereat, a printing telegraph transmitter at each station, means controlled at said transmitter ted from that station, thereby causing similar code impulses Ato be superposed on the beat frequencies produced at both stations, means to detect said code impulses from the beat frequency at each station, a receiving printer at each station responsive to the deat the station which is receiving for interrupting the Wave emitted from that station when it is desired to transmit a break signal, thereby interrupting the beat frequency at both stations so that the receiving printer at the transmitting station will not record the signals transmitted.

10. In a radio signaling system, a plurality of intercommunicating stations, each emitting a Wave of a different frequency, means at each station to produce a beat the Wave emitted and the by interrupting the beat frequency at each station and preventing further operation of the detecting means.

In testimony whereof, I have signed my name to this specification this 26th day of March, 1924.

DONALD B. PERRY. 

